See: https://git.pleroma.social/pleroma/mastofe/tags/bundle-2019-02-10

[ci skip]

Also makes the index a lot smoler.

This reverts merge request !733

This reverts merge request !682

Fixes #552

The previous migration actually created values for the key "id", including the
quotes. This one should fill out all missing ids.

Closes #511

Indices in postgresql rely on operators, so they won't be used if you use only functions.